# Hemisphere S631 / S321

The Hemisphere S631 and S321 are professional GNSS receivers by Hemisphere GNSS (a Unicore Communications company). The S631 is the flagship model featuring a built-in 4G modem, multi-constellation tracking, and advanced RTK performance. The S321 is a compact, cost-effective receiver sharing the same NTRIP workflow. Both receivers are configured through **PocketMax** field software running on an Android controller. The Hemisphere VS330, a marine GNSS compass variant, can also connect to RTKdata via terminal commands or GNSS Toolbox.

## Requirements

* **Hemisphere S631 or S321** powered on with clear sky visibility
* **PocketMax** field software on an Android controller or tablet
* **Internet connection** via the receiver's built-in 4G modem (SIM card — S631) or the controller's cellular/Wi-Fi connection
* **RTKdata.com account** with active RTK credentials (username starting with `rtk` and password from your RTK dashboard)
* **Survey pole** with Hemisphere adapter

{% hint style="info" %}
Don't have an RTKdata.com account yet? [Start 30-day Free Trial](https://rtkdata.com/try-rtk-corrections-free-for-30-days/) or [View Pricing](https://rtkdata.com/pricing/)
{% endhint %}

## Step-by-step setup via PocketMax

{% stepper %}
{% step %}

#### Connect to the receiver

1. Power on your S631 or S321 and wait for satellite tracking to begin (LED indicators confirm satellite lock).
2. Open **PocketMax** on your Android controller.
3. Go to **Config** > **Connect** and select your Hemisphere receiver from the Bluetooth device list.
4. Pair and connect. PocketMax will display the receiver model and current status.
   {% endstep %}

{% step %}

#### Configure the GNSS rover corrections

1. In PocketMax, go to **Config** > **GNSS Rover** > **Corrections**.
2. Select **NTRIP Client** as the correction source.
3. Choose the internet source:
   * **Receiver Modem** — uses the S631's built-in 4G modem with a SIM card inserted. Configure the APN for your carrier if prompted.
   * **Controller Internet** — uses the Android controller's internet connection (phone hotspot or mobile data). This is the typical option for the S321.

{% hint style="info" %}
If using the receiver's internal modem, you may need to configure the **APN** for your mobile carrier. Check the receiver's network settings or consult your carrier for the correct APN.
{% endhint %}
{% endstep %}

{% step %}

#### Enter RTKdata.com NTRIP settings

Fill in the NTRIP connection fields. Select the tab for your region:

{% tabs %}
{% tab title="North America" %}

* **Host / Caster Address:** `rtk.rtkdata.com`
* **Host (IP fallback):** `13.56.117.10`
* **Port:** `2101`
* **Username / Password:** From *RTK Credentials* in the internal dashboard (not website login)
* **Mountpoint (ALL CAPS):** `AUTO`
  {% endtab %}

{% tab title="Europe" %}

* **Host / Caster Address:** `eu.rtkdata.com`
* **Host (IP fallback):** `3.73.41.96`
* **Port:** `2101`
* **Username / Password:** From *RTK Credentials* in the internal dashboard (not website login)
* **Mountpoint (ALL CAPS):** `AUTO`
  {% endtab %}

{% tab title="Australia" %}

* **Host / Caster Address:** `aus.rtkdata.com`
* **Host (IP fallback):** `54.206.56.130`
* **Port:** `2101`
* **Username / Password:** From *RTK Credentials* in the internal dashboard (not website login)
* **Mountpoint (ALL CAPS):** `AUTO`
  {% endtab %}
  {% endtabs %}

{% hint style="warning" %}
Type `AUTO` manually in all capital letters. Do not browse the mountpoint list — PocketMax may time out or return an incomplete list with large casters.
{% endhint %}
{% endstep %}

{% step %}

#### Verify GGA position sending

1. In the NTRIP settings, ensure **Send GGA** (or **GGA Upload**) is enabled.
2. The receiver must have at least a standalone satellite fix before the NTRIP connection starts.

{% hint style="danger" %}
RTKdata requires GGA position data to select the nearest base station. Without GGA, the connection will succeed but no corrections will be delivered.
{% endhint %}
{% endstep %}

{% step %}

#### Start the RTK survey

1. Tap **Apply** or **OK** to save the rover configuration.
2. PocketMax will connect to the internet, then to the RTKdata NTRIP caster.
3. Watch the solution status: **Autonomous** > **Float** > **Fixed**.
4. Once Fixed, you are ready to collect points, stake out, or run your survey workflow.
   {% endstep %}
   {% endstepper %}

## Hemisphere VS330 (marine variant)

The Hemisphere VS330 is a dual-antenna GNSS compass designed for marine applications. It does not use PocketMax — instead, configure NTRIP via **terminal commands** (serial or TCP connection) or **Hemisphere GNSS Toolbox**:

1. Connect to the VS330 via serial port or TCP.
2. Send the NTRIP configuration command with the RTKdata settings (host, port, mountpoint `AUTO`, username, and password).
3. In GNSS Toolbox, navigate to the NTRIP client settings and enter the same parameters as listed in the regional tabs above.

Refer to the Hemisphere VS330 Integration Manual for the exact command syntax for your firmware version.

## Vertical reference (heights)

{% hint style="info" %}
Heights from RTKdata.com are **ellipsoidal**, not orthometric (mean sea level). Configure a geoid model in PocketMax under your project coordinate system settings if your project requires orthometric heights.
{% endhint %}

## Troubleshooting

| Problem                                      | Cause                                          | Fix                                                                                                                |
| -------------------------------------------- | ---------------------------------------------- | ------------------------------------------------------------------------------------------------------------------ |
| No internet connection (Receiver Modem)      | SIM card not active or APN misconfigured       | Verify the SIM card has data. Configure the correct APN for your carrier in the receiver's network settings.       |
| No internet connection (Controller Internet) | Controller has no data connection              | Ensure your Android controller has mobile data or is connected to a Wi-Fi hotspot.                                 |
| Empty mountpoint list                        | Source table timeout or wrong host             | Do not browse — type `AUTO` manually in all caps. Verify the host address is correct.                              |
| No corrections received                      | GGA sending disabled                           | Enable **Send GGA** in the NTRIP settings. RTKdata requires GGA to select the nearest base.                        |
| Stuck on Float                               | Poor sky conditions or far from base           | Move to open sky. Check RTKdata base coverage at [rtkdata.com](https://rtkdata.com).                               |
| Credentials rejected                         | Using website login instead of RTK credentials | Use the username (starting with `rtk`) and password from your RTK dashboard, not your website account.             |
| VS330 not connecting                         | Wrong command syntax or firmware version       | Verify the NTRIP command syntax matches your VS330 firmware version. Use GNSS Toolbox for a GUI-based alternative. |

## Tips and tricks

* **S631's built-in 4G modem** provides the most reliable connection — insert a SIM card and select Receiver Modem to avoid phone hotspot dependency.
* **S321 users** should use Controller Internet and tether the controller to a phone hotspot or use the controller's cellular data.
* **Save the NTRIP configuration** so your crew can reuse it across projects without reconfiguring.
* **Check correction age** in the PocketMax status display. Values above 5 seconds indicate an unstable internet link.
* **Hemisphere receivers support RTCM 3.x** messages — this is the format RTKdata delivers.
* **Keep receiver firmware updated** via Hemisphere's firmware update utility to benefit from the latest RTK engine improvements.
* **For the VS330**, use GNSS Toolbox for easier NTRIP configuration rather than manual terminal commands.